Combined stretch-type straightening apparatus for metal strips

ABSTRACT

In a stretch-type straightening apparatus for a metal strip of indefinite length running therethrough, between a hold-back roll assembly and a drawing roll assembly there is disposed a bending machine having a plurality of power-driven rolls about which the running strip is trained in an S-shaped path. Each roll pair of the bending machine is driven by a differential gearing while every two said differential gearings are driven by a main differential gearing, the input shaft of which is rotated by a motor means. In this manner the rpm of the successive rolls in the bending machine adjusts itself in accordance with the strip elongation from roll to roll, in order to ensure a slippage-free engagement between any of the rolls in the bending machine and said running strip.

United States Patent I [191 Miinchbach Mar. 12, 1974 [54] COMBINED STRETCH-TYPE 3.641,?97 2/1972 Bell et a1 72 205 STRAIGHTENING APPARATUS FOR 3,362,202 1/1968 Gray 72/160 2.432.828 12/1947 Stone 72/160 METAL STRIPS Inventor: Curt Miinchbach,

Pforzheim-Sonnenberg, Germany Assignee: Irma Ungerer, I

Pforzheim-Brotzingen, Germany Filed: May 15, 1972 Appl. No.: 253,263

' Foreign Application Priority Data May 13, 1971 Germany 2123655 U.S. Cl. 72/160, 72/205 Int. Cl B2lb 39/08, B21d 1/04 Field of Search 72/205, 160, 162-165 References Cited UNITED STATES PATENTS ,509 6/1967 Roesch 72/162 ,026 6/1967 Guillot v. 72/163 .737 12/1971 Defontenuy 72/205 Primary Examiner.l\/lilton S. Mehr Attorney, Agent, or FirmEdwin E. Greigg [57] ABSTRACT In a stretch-type straightening apparatus for a metal strip of indefinite length running therethrough, between a hold-back roll assembly and a drawing roll assembly there is disposed a bending machine having a plurality of power-driven rolls about which the running strip is trained in an S-shaped path. Each r011 pair of the bending machine is driven by a differential gearing while every two said differential gearings are driven by a main differential gearing, the input shaft of which is rotated by a motor means. In this manner the rpm of the successive rolls in the bending machine adjusts itself in accordance with the strip elongation from roll to roll, in order to ensure a slippage-free engagement between any of the rolls in the bending machine and said running strip.

5 Claims, 3 Drawing Figures l COMBINED STRETCH-TYPE STRAIGIITENING APPARATUS FOR METAL STRIPS I BACKGROUND OF THE INVENTION This invention relates to a combined metal strip straightening apparatus operating with a stretching pull and having a hold-back roll assembly in which the rolls are arranged in an S-configuration, a drawing roll assembly wherein the rolls are also arranged in an S- configuration, and a strip bending machine having an even number of rolls about which the metal strip is trained in an S-like path.

For the straightening of strips having a smooth surface made of steel, heavy or light metal, stretch-type straightening apparatuses are being used in an increasing extent. Such an apparatus comprises so-calle'd S- roll assemblies formed of rolls of large diameter; one roll assembly serves as a hold-back assembly, while the other serves as a drawing assembly. The strip is trained in an S-shaped path about the rolls and adheres to the rolls by virtue of looping and friction. A strip which runs continuously through such an apparatus is held back by the hold-back assembly and pulled by the drawing assembly. As a result, the strip is stretched to such a substantial extent that its entire cross section will exceed the flow limit and will thus plastically deform and become tension free.

The magnitude of pull to be exerted by the drawing assembly for the stretching and straightening depends upon the material and the cross section of the strip and may be set to a maximum stretching force.

For making possible a satisfactory use of this apparatus in case of strips for which the maximum stretch is no longer sufficient, it is known to dispose between the hold-back assembly and the drawing assembly a bending machine formed of several rolls. In such a combined stretch-type straightening apparatus the strip is advanced with a stretching pull below the flow limit in the range of elastic yield of the strip and by bending the strip in alternating directions about the rolls of the bending machine, additional bending stresses are generated which are superimposed to the elastic pulling stresses in the strip in such a manner that the flow limit of the strip is exceeded. Thus, the plastic condition with the aforenoted tension free state is achieved, together with good straightening results. The strip elongation during the flowing of the material occurs from roll to roll within the roll assembly of the bending machine. A lengthening of the strip from roll to roll, however, makes it impossible to drive the r.olls together in a conventional manner with the same angular velocity by means of a gear assembly, even though the rolls all have the same diameter. In general, this difficulty is circumvented by leaving the bending machine without a drive means and causing the rolls thereof to be dragged by the strip. Such a solution, however, places on the drawing roll assembly the additional burden of bending work which is possible only when the apparatus operates at the maximum drawing output.

OBJECT AND SUMMARY OF THE INVENTION assumes itself the bending function without additionally burdening the drawing roll assembly andwherein each roll of the bending machine may undergo by means of a simple driving arrangement such an rpm adjustment necessitated by the strip elongation from roll to roll that the rolling contact. between any of the rolls of the bending machine and the strip will remain slippage free.

Briefly stated, according to the invention, with each roll pair of the bending machine there is associated a differential gearing and every two differential gearings are driven by a common main differential gearing. By means of this simple arrangement in which all rolls of the bending machine may be rotated by a sole motor, the straightening range of the combined stretch-type straightening machine is'substantially extended without the appearance of slippage or sliding marks on the material which would render the strip worthless.

The invention will be better understood as well as further objects and advantages become more apparent from the ensuing detailed specification of two exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic sectional view of the roll assembly of the bending machine;

FIG. 2 is a schematic illustration of the drive means for the bending machine and FIG. 3 isa schematic illustration of another embodiment of the drive means for the bending machine.

DESCRIPTION OF THE EMBODIMENTS The bending machine schematically illustrated in FIG. 1 comprisesfour rolls 22, 27, 40 and 45 about which a metal strip 46 is trained in an S-like path.

The rolls of the bending machine are driven by a common drive motor (not shown) with the intermediary of a drive gear assembly, two embodiments of which are illustrated in FIGS. 2 and 3. Turning now to the embodiment according to FIG-2, there is shown an input shaft 8 which is rotated by a drive motor (not shown) and to which there is keyed a bevel gear 9. The latter meshes with a bevel gear 7 which, in turn, is' affixed to the housing of a main differential gearing 1. Within the housing there are disposed bevel gears 4 and 5 keyed to respective. shafts 2 and 3 which journal in said housing and which project outwardly therefrom. The bevel gears 4 and 5 are interconnected by means of a compensating bevel gear 6 which also journals in the housing.

The main differential gearing 1 drives two differential gearings l2 and 30. For this purpose, to the shafts 2 and 3 extending from the housing of the main differential gearing 1 there are keyed respective spur gears 28 and 10 which mesh, respectively, with spur gears 29 and 1 l. The spur gear 11 is affixed to the housing of the differential gearing 12, while thespur gear '29 is fastened to the housing of the differential gearing 30.

The differential gearings l2 and 30 are of identical structure and are provided with bevel gears l5, l7 and 33, 35, which are respectively interconnected by compensating bevel gears 16 and 34 keyed to shafts 13, 14 and 31, 32. The shafts 13 and 14 project outwardly from the differential geraing 12 and are connected to bevel gear drives 18 and 23, respectively. The shafts 31 and 32 project outwardly from the differential gearing 30 and are connected, respectively, to bevel gear drives 36 and 41. The output shafts 21 and 26 of the bevel gear drives 18 and 23 (associated with the differential gearing l2) drive the rolls 22 and 27, respectively, while the output shafts 39 and 44 of the respective bevel gear drives 36 and 41 (associated with the differential gearing 30) drive the rolls 40 and 45, respectively. In this manner, with the differential gearing 12 there is associated the first upper roll 22 and the oppositely driven first lower roll 27, while the second differential gearing 30 is associated with the second upper roll 40- and the oppositely driven second lower roll 45. This arrangement makes a separate reversing gear for rolls 27 and 45 unnecessary.

The bevel gear drives 18, 23, 36 and 41 have respective bevel gears 19, 24, 37, 38, and 42, 43. These bevel gears are keyed to respective shafts 14, 21; 13, 26; 31, 39, and 42, 44.

Turning now to FIG. 3, an input shaft 8' rotated by a motor not shown, drives the main differential gearing l of the bending machine through a spur gear 47 keyed to the shaft 8 and a spur gear 48 meshing with the spur gear 47 and fixedly connected with the housing of the main differential gearing l. The latter is arranged in such a manner that the projecting shafts 2' and 3, contrary to the arrangement according to FIG. 2, extend parallel to the drive shaft 8. To the shafts 2' and 3there are keyed, respectively, spur gears 49 and 50 which mesh with further spur gears 51 and 52 of respective intermediate shafts 53 and 54. To the latter there are affixed spur gears 55 and 56 which mesh with spur gears 57 and 58, rigidly secured to the housing of respective differential gearings l2 and Of the shafts 59, 60 and 61, 62, projecting outwardly from the differential gearings 12 and 30, respectively, the shafts 59 and 61 serve directly for driving the rolls 22 and 45, respectively, whereas the rolls 27 and 40 are driven by means of the shafts 62 and 63, each of which carries a respective spur gear 64 and 65 keyed thereto. They mesh with a spur gear 66 keyed to the shaft 60 and a spur gear 67 keyed to the shaft 62. The differential gearings 12' and 30' are so arranged that the shafts 59 and 61 may be connected through clutches, not shown, with corresponding stub shafts of the bending machine.

In the embodiment according to FIG. 3, the opposite rotation of the shafts driven by one and the same differential gearing is achieved by connecting one of the shafts extending from the differential gearing directly with a roll of the bending machine, whereas the other shaft extending from the same differential gearing is connected to the other roll with the intermediary of a gearing comprising two meshing spur gears. In the embodiment according to FIG. 2, the opposite rotation of the roll drive shafts is achieved by connecting the shafts extendingfrom the differential gearing with bevel gear drives arranged in a mirror symmetry. In this manner the drive shafts extending from the bevel gear drives will rotate in opposite directions.

What is claimed is:

1. In a combined apparatus for straightening, by a stretching pull, a metal strip of indefinite length running therethrough, said apparatus being of the known type that has (a) a hold-back roll assembly, (b) a pulling roll assembly disposed downstream of said holdback roll assembly and (c) a bending machine disposed between said hold-back roll assembly and said pulling roll assembly, said bending machine including an even number of rolls about which said running strip is trained in an S-shaped path, the improvement in said bending machine comprising,

A. first differential gearings, each being drivingly connected to a separate roll pair each formed of two different rolls of said bending machine and B. at least one second or main differential gearing,

each drivingly connected to every two first differential gearings.

2. An improvement as defined in claim 1, wherein the two rolls within each roll pair rotate in opposite directions in said bending machine.

3. The improvement as defined in claim 1 wherein said first differential gearings drive one of said rollers of each pair in a direction opposite from the direction of rotation of the other by bevel gears arranged in mirror symmetry.

4. The improvement as defined in claim 1 wherein said first differential gearings lower one of said rolls of each pair in one direction while the other roll of each pair is driven through the intermediary of two meshing spur gears.

5. The improvement as defined in claim 4 wherein the output from said second differential gearing is in parallel with an input shaft driving said second differential gearing. 

1. In a combined apparatus for straightening, by a stretching pull, a metal strip of indefinite length running therethrough, said apparatus being of the known type that has (a) a hold-back roll assembly, (b) a pulling roll assembly disposed downstream of said hold-back roll assembly and (c) a bending machine disposed between said hold-back roll assembly and said pulling roll assembly, said bending machine including an even number of rolls about which said running strip is trained in an S-shaped path, the improvement in said bending machine comprising, A. first differential gearings, each being drivingly connected to a separate roll pair each formed of two different rolls of said bending machine and B. at least one second or main differential gearing, each drivingly connected to every two first differential gearings.
 2. An improvement as defined in claim 1, wherein the two rolls within each roll pair rotate in oppOsite directions in said bending machine.
 3. The improvement as defined in claim 1 wherein said first differential gearings drive one of said rollers of each pair in a direction opposite from the direction of rotation of the other by bevel gears arranged in mirror symmetry.
 4. The improvement as defined in claim 1 wherein said first differential gearings lower one of said rolls of each pair in one direction while the other roll of each pair is driven through the intermediary of two meshing spur gears.
 5. The improvement as defined in claim 4 wherein the output from said second differential gearing is in parallel with an input shaft driving said second differential gearing. 